Torque compensator



Dec. 15, 1953 R. G. BALLARD ETAL TORQUE COMPENSATOR 2 Sheets-Sheet l Filed Deo. 22. 1949 Inventors: Robert G. Bal lard, John E. Lundberg, www1-@6 WW Their Attorney.

Dec. 15, 1953 R. G. BALLARD ErAL 2,662,410

TORQUE coMPENsAToR v yFiled Dec. 22. 1949 2 Sheets-Sheet 2 Patented Dec. 15, 1953 UNITED STATES VvOF FICE TORQUECOMPENSATOR Robert f G. Ballard, Saugus, #and 'rJohn-EJ Lundberg, Lynn; Mass., assignors' toA GeneralV Electric Company, a corporation of -New :York

Application December 22, 1949,`Serial No. 134,548

Claims.

11 ,The present invention relatesrto torque. compensating systems and, more particularly, to varrangements for minimizing the net torque be- .tween relatively rotatable gyroscope members ,in-

terconnected by current-conducting spirals.

Flat spiral springs have long been vsatisfactorily .employed to` conduct current between elements `.which are to be angularly .displaced and which `are not adversely affected by the `springaction thereof, (as, for example, in moving coil instru- V'ments wherein the spiral springs also -serve to return a pointer to a neutral position .when curr-ent ceases. Sncecurrent-conducting spirals do not voccasion the undesirable friction and contact vresistance which are experienced with slip-ring structures, these spirals maybe of V,utility in acucomplishing the excitation oan electricgyroscope `motor by translating the electric power :from conductors on a gimbal to the motor mount- ;ed on a frame pivoted with thevgimbal. However, insensitive gyroscopel apparatusvdeflections `oi the spirals from a neutral position introduce torques between the gimbal and motoru frameand :thereby create objectionable precession. In...ac

acting members coupled with-.each of the-.rela- .tively rotatable units connected by -thev current- -conducting spirals. Further, -.the .net v.torqlle versus angular displacement Ycharacteristics eX- vhibited by the compensator-structure --alone `oloitains from the resultant of=a,-;:lurality-v of indi- -vidual characteristics ,Y produced Iby ,magnetically interacting members.

,It -is therefore one object of the-presentinvention to provide a torque compensator-which produces a predetermined torque,versus-angularydisplacement characteristic betweenrelatively vrotatable members by themagnetic interactionbetween elements carried by-saidmembers,

A second object is to provide Vmagneticallyinteracting means for eliminating net torqnesintroduced by spirals coupled between the mctorframe and `supporting gimbal 'of ,agyroscope over -asubstantially 180 degree range 'of displacements.

AVA;dditionally it is an object-,t0 vprovide ia plu- ,ralitvof magnetically interarita1` g-.members..-hav

ving -afresultant torque versusangular displace- -ment characteristic-which just neutralizes vthe torque o versus Y displacement characteristic of a, "spiral structure coupled between'a gyroscope -motor frame "andgimbal.

AThese and other'objects and features of #this invention vmay be most effectively observed with reference to the-following description `andthe accompanying drawings, wherein:

Fig. 1 depicts `graphically the torque characteristicsv-of a'spiral Aconductor-and compensator arrangements therefor;

`Fi g.' '2 illustrates-iin anaxial cross-section view,

l`a portion Aof aoatedgyroscope type instrument incorporating current-conducting spirals-and =a i preferred torque "compensator structure;

Fig. 3 presents'a pictorial Viewy of-a torquecompensator such `as that-oi Fig. 2; and

Figsy 4.and- 5 pictorially represent additional embodiments 'of torque compensating arrangements.

nllnFig;1,'thestraight-line plot I is illustrative of "the counterclockwlse and clockwise torquey introduced between Itwo relatively rotatable v'mem- :bers by spiral'concluctorsor springs asy the members are angularly displaced up to degrees in `the clockwise and Acounterclockwise directions respectively from-'that position in which the'spiral is at neutral equilibrium, and it -should be v"observedthat ,the equation for this plot is: 'T1-:Ka `wliere'Ti is the spiral torque, K is a constant V,dependent upon the spiral construction andnumber of. spirals, and a is theangulardisplacement f the attached members. The plot `2 is that of the torque 'T2 which must be applied between Athe @rotatable members to exactly overcome the spiral gtorque, ,with the sense of this 'former'torque reversed with respect Lto the latter Vsuch that a clockwise spiral torque will be just neutralized` by a ,counterclockwise Vcompensator torque, and vice versa. 'A,reductionof` the` net torque' betweenl the .rotatablemembers to zero for all angular 4disq placements ,uplto and including 90 degrees inboth Ldirectionsf'from a neutral position thus requires "thatithe compensator device also have the' characteristic T2=iK, where T2 is theresultant com- ,.pensator torqueequalto the spiral torque butof opposite-sense'K is a constant, Vand a isftheangular displacement between the rotatablemembers. VAs explained in detail hereinafter, ,this colpensator. torque characteristic may be readily produced by .compensator elements which -conuenientlvyeld the torque characteristics and T4=Ka-a sin e, which are plots 3 and 4, respectively, in Fig. l. From a summation of these characteristics it is apparent that which is the desired resultant.

Particularly advantageous utilization of this invention, though not limited thereto, appears in its application as a compensator for the torque introduced by spirals between the rotor bearing member and gimbal support therefor in a floated gyroscope type instrument illustrated in part in Fig. 2. For a more detailed disclosure of such instruments wherein the entire gimbal and rotor bearing members in combination are immersed in a liquid such that the weights thereof are just supported by the liquid, reference should be had to the copending application of F. V. Johnson and F. R. Fowler, Serial No. 171,582, led July 1, 1950, for Floated Gyroscopes, assigned to the same assignee as that of the present application. 1n the floated gyroscope of Fig. 2, the gimbal and rotor bearing member E are pivotally coupled by the journalling shaft 1 and sensitive low friction bearing S, and, in accordance with the teachings of the above noted copending application, the rotor bearing member 6 included a fluid-tight container 9 which prevents fluid from reaching the gyro rotor IQ, shown in part, and the motive means therefor, not illustrated. The entire structure, inclusive of the rotor bearing member t, gimbal 5, and the torque compensator arrangement I i of this invention, is buoyed by the liquid I2 which fills the remaining volume between the container S and the liquid-tight outer casing I3. Frictional restraint of rotation between gimbal 5 and member 6 is so minute in the iloated instrument that spiral current conductors I4, which may serve to translate the power from leads I5 on gimbal 5 to the gyro motor supply leads IB within container 9, would apply torques which would cause intolerable precession unless compensation therefor were introduced. Accordingly, the compensator structure designated generally by the numeral II is coupled with both member 6 and gimbal 5 and applies therebetween the torques T2 of plot 2 in Fig. 1 to just neutralize the equal but opposite torques of spirals I4. Compensator H includes two annular non-magnetic plates I1 and IS, which are spaced from one another and which are amxed to the projection I9 of member Ei coaxially with the journalling shaft 1, and a third annular non-magnetic plate positioned intermediate plates I1 and I8 and afiixed to gimbal 5 and spaced from projection IS by supporting members 2l. The plates I1, 20 and I8, which may, forexample, be constructedof aluminum, carry' annular permanent magnet vstructures 22, 23 and 24, respectively, and theinfinay be more easily comprehended with reference to` Fig. 3 which views pictorially portions of the assembly shown by Fig. 2 when spirals I4 are in .the stable centralized position, neither wound nor unwound. lt should be apparent that relative angular displacement between plates. I1 and I8,

Viixedly held by projection I9, and the intermediate plate 2Q, held by gimbal 5, occurs when the gimbal and rotor bearing member 6 are similarlyl displaced, and the magnetic interaction between magnetic structures 22 and 24 and the interlli) mediate magnetic structure 23 creates the desired n' 24 is magnetized diametrically with its magnetic poles substantially along a diameter of the plate, the arrangement being such that south (S) poles are innermost and north (N) poles outermost on one-half of this diameter, and the reverse polarization exists on the opposite half. Magnetic plate 23, with which plate 24 interacts, is comprised of a small sector 25 and a larger sector 26, both of which sectors are radially polarized with the directions of polarization reversed from one another. When plates 24 and 23 are initially oriented as shown in Fig. 3, the poles of plate 24 are disposed opposite the centers of the two sectors of plate 23 and no relative torque is exerted between plates. However, any increment of displacement between these plates results in an instability, due to the fact that like poles are oppositely disposed, which tends to cause relative angular displacement therebetween until opposite poles are oppositely disposed and the plates are just 180 degrees displaced from the position illustrated. The torque versus angular displacement characteristic for the first degrees of displacements between these plates is shown as plot 3 in Fig. 1, the torque T3 being A sin a, where A is a constant which is a function of pole strengths, plate spacings, and plate widths. The sector 25 is preferably selected to have an angular width of approximately degrees, the selection of this width being determinative of the substantially sinusoidal relationship between the torque and displacement, although it should be understood that this function is merely illustrative and may be other than sinusoidal with equivalent results. Annular plate 22 is also comprised of a small sector 21, of about 110 degrees in angular width, and a larger sector 28, both of which are radially polarized, with the directions of polarization reversed from one another. When plates 23 and 22 are initially oriented as illustrated in Fig. 3, the smaller sectors 25 and 21 are 180 degrees displaced and no relative torque is experienced even though unlike poles are oppositely disposed over the sector angles. Since the larger sectors 26 and 23 have substantially uniform polarizations over their center portions, the increase in the tendency of the oppositely polarized smaller sectors 25 and 21 to align themselves is only slight for small angles of initial displacements and rises substantially only beyond about 30 degrees, such that the torque Versus displacement characteristic up to about 90 degrees is substantially that of plot 4, Fig. l, that is, T4=KaA sin a. The constants may be adjusted by the appropriate proportion- .Y ing of pole strengths, plate spacings, and plate widths, while the function of torque with reference to displacement may be fixed by a proper selection of the angular widths of smaller sectors 25 and 21. In the compensator structure set forth, the resultant torque characteristic is the summation of the two characteristics produced by the interaction of both plates 22 and 24 with the intermediate plate 23, and this resultant is that of plot 2, Fig. 1, which is substantially equal and opposite to the spiral characteristic. for displacements between gimbal 5 and the rotor bearing member 6 up to 90 degrees in either direction from a neutral position, the effective torque is negligible.

' lAnother embodiment of a torque compensator Vin' naccordant'ze with this invention is represented "in Fig. 4 and is shown to include two units 29 and 30, each independently producing one of the required torques Relative angular movement between' the shaft 3l amd member 32 is contemsplatednarid eetileesteeneespiral ai nsf connected :therebetween a 23 fincludes a criminal member 34 attached toi-shaft 3-l fanden :outer -annuiar-r-crlinereal member fexedfte `memv`b ervi2. Membersskand 35 are,each polarized 2; along a diameter,y and itisapparent that the torque therebetween-will beiequal tof-A sine, or/:that

fof lplot E31 intFig.; 1. .Unitli aldo:compri ses Erey-- i lindricalfmember attachedtojshait 3 I and an outer i annular cylindrical member 31 y.supported .by member .32. ,Cyli-ndrical-members;and 31 -are radiallyl polarized,and.eachhas a small sector 38 and `3 9, respectively,- which hasaradial `po lar ization opposite to thepolarization ofgthe remainder ofthel .member :and in these-me; radial direction .as the other small sector. As in the .arrangement of 3, these sectors are; 180l degrees removed rat the neutral orzero torque'position, and the torque characteristic,-.such;asaplot vv4 in Fig..r1, is achieved vbyfa similaremagnetic'interaction.

Fig. Tv illustrates .alternative structures .for reatingthe required compensator torqueslfbe- .tween ftwo. relatively :rotatable-` elements -40 Vand ,4L 4The. rod-shapedqmagn'et `ill-produces a tor- ,que equal. to A` singain vcooperation with thecshaped magnet 43, it beingclear. that this. torque characteristic isone which may beachieved by ,any permanentv magnet rotatable in a unidirectional eld. The .torque K a*A.sin a, is obtained kin this, embodiment by the permanent magnet, in operative ,relationship VV.withthe member constructed of magnetic material which is. shaped and disposed to provide the desired characteristic. {Member 45 is nattracted to magnet v44 lsuch ,that it will orientlitself .to oder thelowest reluctance ments both mag-netized and of Amagneticv materials, and that the resultant torque characteristics may-be other-than linear if such compensation is required. Additionally, `the structuresdisclosed mayV be adapted to serve spring ratherthan ,i

compensator functions, with the characteristic of either plot I or plot 2 of Fig. 1.

While particular embodiments of the subject invention have been shown and described herein, these are in the nature of description rather than limitation, and it will occur to those skilled in the art that various changes, modifications and combinations may be made Within the province of the appended claims without departing either in spirit or scope from this invention in its broader aspects.

What we claim as new and desire to secure by Letters Patent of the United States is:

l. In an arrangement including two relatively rotatable parts coupled together by a resilient spiral structure which produces torque variable with relative rotation of said parts, a torque compensator comprising a first magnetized member affixed to one of said parts, a second magnetized member aixed to the other of said parts, said s l fdlrstefmdiseeondamcmberseheinggpositioned and \-.I.11e&n.izedseuch the @torquet therebetween the@ interact f theirinagnetic"eldsyis A rally propo alito the sine .ref .thevanguiar displacement.therebetween and in an-anregular gdirectionppposite gto; thatfof .the Lspiral stnzcture tural-1e;j andathird Amagnetized member :aixed toesad `other apart, if said Vfirst and third @memberszbeingz,positioned and magnetized/ such .,:thatrthe torquetherebetween"due.to the interactionvofy their magnetic,- fleldsis substantially equal ltothe\spiral@structure;'torque :less the; torque be- ;.tweensaid firstzandisecond membersfand -in-an qangular; directionrbpposite rto .that ,of the ,spiral .,structureetorque.

' 2. :Inliani arrangement'. including two relatively rotatable parts coupled together by .a resilient spiral .structure i which produces4 torque -variable 'iwithi relat-vefrotation fof said. parts susceptible to itorqueby relative"-ro tation ofsaid parts, a. torque @compensator comprisingiirst meanscoupled .with @saidparts magneticallyfinteracting .to producen torque fbetween. LsaidY parts substantially .propor- -tional1 to the zsineof the -angular displacement therebetween and? in fa direction opposite v tov that of the spiral structure.torquerandisecond means coupled vwith saidparts magnetically interacting toprodueea torquebetween said parts substani tially equal'r to -said "spiral'lstructure torque less the'- torque of said iirstfmeansand in Van langular direction Opposite toithat of said spiral structure torque l3. An arrangement 1for producing between relatively rotatable partsv torquesfwhich increase "linearly'with-*angulardisplacements from-a neu- -trarpositiongand-which actA in Vthe same angular direction-vas' said-displacements, vcomprising first magnet-ized'means coupled-withcne of said parts, 'second Amagnetized means 'coupledv with another of-said -iparts,- said first-and second means being positionedand ma'gnetized-such that the torque t-herebet-ween due-to'fthe interaction of their magnetic fields is *substantially proportional to Athe sineeof theangula-r displacement therebetween and -in angangularvfdirection tending to increase said displacement, and third--magnetized means coupled with s aidlother part, said rst-fand third Ymeans being positionedand-magnetizedsuch that the Ytorque'therfebetween dueto the interaction of their magnetic-'heide is substantially equal to said linearly increasingtorque less the torque, between ksaid inst-and second means and in an angular 'direction tending `to increase displacement from said neutral position.

v4. 'In' an arrangement including two relatively rotatable parts coupled together by a resilient lspiral structure, the torque compensator comprising a rst member mounted on one of said parts and producing a unidirectional magnetic iield, a second member mounted on the other of said parts and having magnetic poles along one axis thereof, said second member being disposed in the field of said first member, and means coupled with said parts magnetically interacting to produce a torque between said parts substantially equal to the spiral structure torque less the torque between said rst and second members.

5. An arrangement as set forth according to claim 4 wherein said means comprises a permanent magnet coupled with one of said parts, and a plate of magnetic material coupled with the other of said parts shaped and disposed to produce said torque between said parts in tending to align itself to provide the lowest reluctance path for the flux from said magnet.

6. In a gyro instrument having a spiral current conductor arrangement between the relatively rotatable rotor bearing structure and gimbal support therefor, a compensator for torque introduced by said spiral arrangement comprising a first plate coupled with said rotor bearing structure and magnetized in one direction along a diameter thereof, a second plate coupled with said gimbal and disposed coaxially and proximately with said first plate, said second plate having a small sector magnetically polarized in one radial direction and a large sector magneticallypolarized in the opposite radial direction, and a third plate, coupled with said rotorbearing structure coaxially and proximately with said second plate, having a small sector magnetically polarized in said opposite radial direction and a large sector magnetically polarized in said one radial direction, said plates being disposed, when no angular torque is exerted by said spirals, such that the small sectors of said second and third plates are substantially 180 degrees displacedand such that the half of said first plate diameter polarized the same as the small sector of said second plate is substantially aligned with the center of said small sector of said second plate.

7. In a gyro intrument as set forth in claim 6, the compensator wherein said small sector of said second plate is about 110 degrees in angular width, and wherein said small sector of said third plate is about 110 degrees in angular width.

8. In a gyro instrument having a spiral current conductor arrangement between the relatively rotatable rotor bearing structure and girnbal support therefor, a compensator for torque introduced by the spiral arrangement comprising a iirst magnetizedv plate coupled with said rotor bearing structure, a second magnetized plate coupled with said gimbal coaXially and proximately with said first plate, said first and second plates being magnetized and disposed Ysuch that the torque therebetween due to the interaction of their magnetic elds is substantially proportional to the sine of the angular displacement therebetween and in a direction opposite to that of the spiral arrangement torque, andl a third magnetized plate coupled with said rotor bearing structure coaxially and proximately with said second plate, said second and third plates being disposed and magnetized such that the torque therebetween due to the interaction of their magnetic elds is substantially equal to said spiral arrangement torque less the torque between said first and second plates and in a direction opposite to that of said spiral arrangement torque,

9. In an arrangement including two relatively rotatable parts coupled together by a resilient spiral structure, a torque compensator comprising a rst member mounted on one of said parts and having magnetic poles along one axis thereof, a second member mounted on the other of said parts and producing a unidirectional magnetic iield, said rst member being disposed in the eld of said second member, a cylindrical member coupled with one of said parts having a small sector magnetically polarized in one radial direction and a large sector magnetically polarized in the opposite radial direction, an annular cylindrical member coupled with the other of said parts and disposed coaxially and proximately with said cylindrical member and having a small sector magnetically polarized in said opposite radial direction and a large sector magnetically polarized in said one radial direction. both of said small sectors being about degrees in angular width.

10. An arrangement for producing between relatively rotatable parts torques which increase substantially linearly with angular displacements of said parts from a neutral position and which act in the same angular directions as said displacements, comprising rst means coupled with one of said parts, second means coupled with the other of said parts, said rst and second means being disposed and constructed to interact magnetically to produce a torque between said parts substantially proportional to the sine of the angular displacement therebetween and in the same direction as said displacement, and third means coupled with said other part, said first and third means being disposed and constructed to interact magnetically to produce a torque between said parts substantially equal to said linearly increasing torque less the torque between said first and second means and in the same direction as said displacement.

ROBERT G. BALLARD. JOHN E. LUNDBERG.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 2,126,855 Wunsch et al Aug. 16, 1938 2,209,735 Lauck 1 July 30, 1940 2,246,738 Lauck June 24, 1941 2,298,573 Little Oct. 13, 1942 2,401,160 Jewell May 28, 1946 2,420,607 Mendelsohn May 137 1947 2,504,170 Wong Apr. 18, 1950 

